ABB Speed Stack RTD has zero sugar, 5 calories, and one measly little carb. Speed Stack contains 250mg of caffeine, plus a 960mg MethXanth Stack packed with DMAE, Guarana, Yerba Mate, Theobromine, Synephrine, Octopamine, and just about any other "ine" you'd want before your next workout or competition. This is one serious liquid power stack.*